Two-way overrunning clutch mechanism



April 30, 1968 R. c. BOWERS ETAL 3,380,563

TWO-WAY OVERRUNNING CLUTCH MECHANISM 2 Sheets-Sheet l Filed March 14,1966 ATTORNEY R. c. Bowl-:Rs ETAL 3,380,563

TWO-WAY OVERRUNNING CLUTCH MECHANISM pril 30, 1968 2 Sheets-Sheet 2Filed March 14, 1966 rqlllllll/lllll/lllllllllllllli i ATTORNEY UnitedStates Patent O 3,380,563 TWG-WAY OVERRUNNING CLUTCH MECHANISM Roy C.Bowers, Northbrook, and Russell E. Silberschlag, Glen Ellyn, Ill.,assignors to Borg-Warner Corporation Chicago, Ill., a corporation ofIllinois Filed Mar. 14, 1966, Ser. No. 534,057 7 Claims. (Cl. 192-44)ABSTRAC'I` 0F THE DISCLOSURE A two-Way overrunning clutch isautomatically conditioned for operation in either direction according tothe direction of rotation of the input shaft. A drag spring engaged withthe grippers has a portion wrapped about a nonrotatable member whichserves to ground the gripper when the clutch is not rotating. Rotationof the clutch unwraps the drag spring from the nonrotata'ble memberreleasing the grippers for rotation with the clutch assembly.

This invention relates to clutch mechanisms, and particularly toclutches of the two-way overrunning type.

A principal object of this invention is to provide a clutch unit whichwill transmit rotation in either direction in response to changes indirection of rotation of a driving member, and which will allow thedriven member to overrun the driving member in the direction ofrotation.

Another object of this invention is to provide a novel means for holdingthe clutching unit in a disengaged position while the direction ofrotation of the driving and driven members is being reversed.

A still further object of this invention is to provide in the aboveclutch unit a drag spring for holding the gripping elements out ofclutching engagement with the associated race means while the directionof driving engagement is being reversed.

The above and other objects and advantages of the invention will be morereadily apparent when read in conjunction with the accompanying drawingsin which:

FIGURE l is a sectional view in elevation of a roller clutch mechanismpositioned between driving and driven mem-bers;

FIGURE 2 is a side view in elevation showing the construction of aportion of the clutch mechanism of FIGURE l;

FIGURES 3 and 4 are views of the roller cage of FIG- URE l;

FIGURE 5 is an elevational side view of one of the end caps of FIGURE 1;

FIGURE 6 illustrates one form of drag spring used in the clutchmechanism;

FIGURE 7 is a sectional view in elevation of a clutch deviceillustrating a second embodiment of the invention;

FIGURE 8 is a View in elevation taken along the line 8 8 of FIGURE 7;

FIGURE 9 illustrates a form of drag spring used with the clutchmechanism of FIGURES 7 and 8.

The broader aspects of the present invention contemplate a clutch devicewhich, when interposed between a driving and driven member, will beeffective to drive the driven member in either direction and at the sametime permit overrunning of the driven member in the direction it isbeing driven at the time. This invention also contemplates includingmeans within the clutch mechanism itself for effecting disengagement ofthe clutch during the interval of reversal of direction of rotation.

Referring now to the drawings, FIGURE l illustrates a preferredembodiment of the invention in which 10 designates a clutch assembly inplace between a pulley 12 Patented Apr. 30, 1968 and a shaft 14. Forpurposes of illustrating the invention, the pulley 12 will `beconsidered a driving or input member and the shaft 14 a driven or outputmember. A belt or other suitable -means connects the pulley 12 to adriving motor (not shown) which is operable in either direction. Thedriven shaft or output member 14 is adapted to be connected to othermembers such as pulleys or gears which may require driving in eitherdirection. Such a connection may be made, for example, to the washer tubof a clothes washing machine, as it may be desirable to change thedirection of tub rotation during a washing cycle.

The clutch assembly 10, illustrating a first embodiment of theinvention, comprises an inner race member 16, an outer race member 18, aplurality of wedging or gripping elements in the form of rollers 20, acage member 22 for supporting and spacing the rollers 20, and a dragspring 24.

The inner race member 16, here considered as part of the driven member,is secured to the driven shaft 14 by keying or other suitable means. Therace member 16 includes a cylindrical surface 26 and a hub 27 adapted torotatably support the cage member 22.

The outer race member 18, here considered as part of the driving member,is secured to the pulley 12 by a plurality of rivets 28. The race member18 (FIGURE 2) includes an annular surface 30 inwhich are formed aplurality of pairs of cam surfaces 32 and 34, spaced circumferentially.The cam surfaces 32 and 34 are opposed ramps forming arch-likeconfigurations which meet at peak points 36. The device illustrated hassix such pairs of cam surfaces, but a greater or lesser number of pairscould be used.

A gripping element, roller 20, is associated with each pair of camsurfaces 32 and 34. The roller 20 is adapted to Wedge between the camsurface 32 and the inner race surface 26 during clockwise rotation, andbetween cam surface 34 and inner race surface 26 during counterclockwiserotation as viewed in FIGURE 2.

The cage member 22 (FIGURES 3 and 4) is an annular member comprising anaxially extending portion 38 which includes a plurality of openings orwindows 40 for receiving the rollers 2). An annular flange 42, radiallyinwardly extending from one edge of portion 38, defines an opening 44which is adapted to receive hub portion 27 of the inner race member 16,the diameter of opening 44 being a fewv thousandths of an inch largerthan that of the hub portion 27. On the opposite edge of portion 38 is aradially outwardly extending annular flange 46, the outer diameter ofwhich is only a few thousandths of an inch less than the diameter of thecircle defining the cylindrical surface 30 on the outer race member 18.Thus, by virtue of the flanges 42 and 46, the cage member 22 is closelyradially confined between the inner and outer race members. The purposeof arcuately extending slot 48 in the flange 46 will be more fullyexplained later.

Two substantially similar axially spaced annular end cap members 50 and52 (FIGURE 1) confine the rollers and cage member. The end cap 50comprises an axially extending annular flange 54, a radially outwardlyextending flange 56 attached to flange 54, an axially extending flange58, and a radially outwardly extending flange 60. Flange 58 connectsflanges 56 and 60.

End cap 52 comprises flange members 62, 64, 66 and 68 correspondingrespectively to flange members 54, 56, 58 and 60 of end cap 50. Onedifference between the end caps 50 and 52 is that in flange 64 of endcap 52 there is formed an arcuate slot 70 (FIGURE 5) extending throughan arc of about degrees, the purpose of which will be later explained.

Bearing members 72 and 74, here illustrated in their preferred form asball bearings, journal the end cap members 50 and 52 on the shaft 14from Within flange members 54 and 62 respectively. It is noted that theouter racc member 18, positioned between the flange portions 60 and 68of end caps S0 and 52 respectively, axially spaces the end cap members.It is further noted that the resultant spacing between anges 56 and 64of the end cap members is effective to axially position cage member 22,flanges 42 and 46 of the latter being positioned closely adjacent theradially extending flanges S6 and 64 of the end cap members. The radialposition of axially extending flanges 58 and 66 of the end cap membersis such that it forms a close lit with the cylindrical surface 30 of theouter race member 18.

A bushing 76 is journalled on the outer surface of axially extendingflange 62 of end cap member 52, permitting rotation of the end capmember 52 with respect to the bushing. The bushing 76 is fastened to astationary portion of the device in which the clutch mechanism isincorporated, secure against rotating movement relative to that device.The bushing 76 may be made of a powdered bronze material, for example.

The drag spring 24, here shown in the form of a torsion spring, isfitted around the bushing 76. The torsion spring may be formed of one ormore loops depending on the desired strength characteristics. At eachend of the spring are prongs or tabs 78 and 86 (FIGURE 6) which, in theassembled clutch mechanism, are received through the slot 70 in the endcap S2 and extend into the slot 48 in the flange 46 of the cage member.The tabs 78 and 80 are long enough to engage the edges 48a and 48h ofthe slot 48. The free diameter of the drag spring 24 is smaller than theouter diameter of the bushing 76 and thus it needs to be unwoundslightly to be placed on the bushing. Thus in the assembled relation africtional t exists between the bushing and the torsion spring member.

To confine the drag spring axially, a drag bushing flange 82 may bepositioned around the bushing '76. Additionally, an annular closuremember 84 is positioned around the bushing 76 and serves to conline boththe bushing ange S2 and the drag spring 24. The closure member 84, thetwo end cap members 50 and 52, the outer race member 1S and the pulley12 are secured together by a suitable means, preferably a plurality ofcircumferentially spaced rivets 28 (see FIGURE 1).

In operation, rotation of the pulley 12 and the attached outer race 18in a clockwise direction (as viewed in FIG- URE 2) is effective to Wedgeroller 20 between the inner race surface 26 and the cam surface 32. Thisdrives the inner race member 16 and the attached shaft 14 in a clockwisedirection. The bushing 76, as previously explained, is attached to astationary part of the device in which the clutch is incorporated anddoes not rotate, since the drag spring 24 is in effect clamped to thebushing 76, it will not rotate unless released. With the rollers inengaging position, as the outer race member rotates clockwise it carrieswith it the cage member 22. As the cage member 22 rotates, the edge 4812of the slot 48 contacts tab 80 of the drag spring, thus expanding thedrag spring, and the frictional hold of the drag spring on the bushing76 is reduced. As long as the driving member, pulley 12 continues torotate clockwise, the expanded drag spring rotates around the bushing76. At this stage it is also possible for the driven shaft 14 with theattached inner race member 16 to overrun the driving member 12 in theclockwise direction.

When the direction of rotation of the driving member 12 is to bereversed to counterclockwise, the member 12 6 must necessarily slow downand come to a stop for a very short time interval before startingrotation in the reverse direction. As this stopped position isapproached during the slow-down, the edge 48h exerts less and lesspressure on the spring tab Si?. Thus the drag spring 24 70 is allowed tocontract and exert an increasing frictional clamping force on thebushing 76. In exerting this increased frictional drag force the spring24 prevents the cage and rollers from moving during the instant when thedirection of rotation of the driving member 12 is 4, reversed. With thecage and rollers thus held stationary, the driving member 12 and theouter race member 18 to which the member 12 is attached shift tocounterclockwise rotation (as viewed in FIGURE 2). Under thesecircumstances, the rollers 20 will be wedged between the cam surfaces 34of the outer race and the inner race surface 26. In addition, the cagemember 22 will now be carried counterclockwise and the edge 48a of theslot 48 of the cage member will push against the spring tab 78. Thisexpands the drag spring 24 and its frictional hold on the bushing 76 isreduced. As long as the driving and driven members 12 and 14 are engagedand continue their counterclockwise rotation, the drag spring 24 willremain in its expanded condition and rotate on the grounded member, thestationary bushing 76. If the speed of the driven shaft 14 is increasedby other means above the speed of the driving member it will be free tooverrun the driving member in the direction it is being driven, in thisinstance counterclockwise.

This drag spring feature constitutes one of the very important featuresof this invention. It effectively provides a two-way clutch which isoverrunning in both directions and provides simple means within thedevice itself for accomplishing reversal of rotation direction of adriven member as that becomes desirable.

FIGURES 7, 8 and 9 illustrate a second embodiment of our invention. Thisembodiment includes two cylindrical race surfaces, one of which iseccentric with respect to the other, and roller wedging means betweenthe two eccentric race surfaces effective to lock the races together.

Reference character 110 designates a clutch assembly in place between apulley 112 and a shaft 114. The pulley 112 will be considered to be adriving or input member and the shaft 114 a driven or output member. Thepulley 112 is adapted to be connected to a driving motor (not shown) bya suitable driving belt. Again the driving motor may be driven in eitherdirection, again the driven shaft or output member 114 may be connectedto other members, such as pulleys or gears, to drive other elements.

The clutch assembly 110 comprises an inner race member 116, an outerrace member 118, a roller wedging element 120, and a drag spring 124.The diameter of drag spring 124 is expanded by spreading prongs 144, 146whereas spring 24 is expanded by pinching prongs 78, 80 toward eachother.

The inner race member 116 may be secured to the shaft 114 by keying,splining or other suitable means, and has a cylindrical surface 126which is concentric with the driven shaft 114.

The outer race member 118 defines an axially extending cylindrical racesurface 130 which is disposed eccentrically with respect to thecylindrical surface 126 of the inner race member. The outer race member118 is supported in a substantially cup-shaped housing 132, which issecured to the pulley 112 and thus forms part of l" 5 the drivingmember.

A bushing 134 forms a bearing member for rotation on the inner racemember 116 and has a recess 135 formed at the inner end which serves tosupport the pulley driving member 112.

At the left side of the device (as viewed in FIGURE 7) this shaft 114 isjournalled in bushing 136; which is grounded against rotation. Thisgrounding is accomplished through connection to tang portion 138 ofmember 140 which is secured to shaft bearing 142.

This drag spring 124 is a torsion spring which in its normal Conditionhas a smaller diameter than the bushing flange 137 on which it ismounted. Thus in its mounted condition in the clutch assembly it exertsa clamping force on the bushing 136 in the same manner as the dragspring 24 of the first embodiment. In the mounted position the spring isrestricted from axial motion by flanges 148 and 150. The drag spring 124has two axially extending spring end tabs 144 and 146, which areeffective to cage the single roller wedging element 120 disposed betweenthe inner and outer race surfaces. The sum of the diameters of thecylinder defined by cylindrical surface 126 of the roller wedgingelement 120 is slightly less than the inside diameter of the cylinderdefined by the outer race surface 136. Thus it is apparent that theroller 120 is only capable of moving between the two extreme positionsshown by the full line and the dotted line in FIGURE 8.

An end cap member 152, attached to the pulley 112 and housing 132, formspart of the enclosure for the clutch mechanism.

In operation, rotation of pulley 112 in a clockwise direction (as viewedin FGURE 8) will wedge the roller 120 between the inner and outer racesurfaces 126 and 130 as shown by the solid line position of the roller.This movement will be suicient to move the roller 120 against the springend tab 146, unwinding the spring 124 and lessening frictional contactof the spring with the bushing 135 to the extent that the spring willfreely rotate on the bushing. With the roller 120 in this position, theshaft 114 is free to overrun the driving member in the clockwisedirection.

When the direction of rotation of the driving member 112 is reversed,there is an interval of time during which no motion is transmitted tothe roller 120. During that time, the spring again coils up tightly withthe spring end tabs close to the roller, and is effective to cage theroller and hold it out of wedging engagement with the race surfaces.Then, as the pulley and the eccentric outer race move in acounterclockwise direction (as seen in FiG- URE 8), the roller assumesthe relative position with respect to the race surfaces as shown by thedotted line. The roller now pushes on the spring end 144, tending tounwind the spring and reducing the drag torque produced between thespring and bushing iiange 137 on which it is mounted, so that the springrotates rather freely on the ange 137. Under these conditions the shaft114 is free to overrun the driving member in the counterclockwisedirection.

Thus it is seen that this invention advantageously provides a clutchunit which can transmit rotation in two directions, as well as allow thedriven member to overrun the driving member in the direction it is beingdriven at the time.

While certain embodiments of the invention have been specificallydisclosed, it is to be understood that the invention is not limitedthereto, as many variations will be apparent to those skilled in theart; and the invention is to be given the fullest possibleinterpretation within the terms of the following claims.

What is claimed is:

1. A two-way engaging device comprising: a rotatable driving member anda rotatable driven member, one of said members defining an inner raceand the other of said members defining an outer race; gripper meansdisposed between said inner ,and outer races for selectively providing awedgingly engaged drive between said driving and driven members to allowfor joint rotation thereofin either a clockwise or counter-clockwisedirection; a stationary member supporting one of said rotatable members;and holding means for selectively securing and releasing said grippermeans with respect to said stationary member, said holding meansincluding a yieldable brake member portion engageable with saidstationary member and a connector portion engageable with said grippermeans, said yieldable brake member portion yielding toward tighterengagement with said stationary member for momentarily securing saidgripper means with respect thereto responsive to reversals of rotationof said rotatable members, and yielding away from engagement with saidstationary member for releasing said gripper means therefrom responsiveto rotation of said rotatable members.

2. The device according to claim 1 wherein said gripper means isrotatable, said braking means including a spring member mounted forrotation with said gripper means and adapted for increased frictionalengagement with said stationary member while the direction of rotationof said engaging device is being reversed, land being biased fordecreased frictional engagement with said stationary member when saiddriving and driven members are engaged with each other for rotation as aunit.

3. The device yaccording to claim 2 wherein said stationary memberincludes a cylindrical surface concentrically disposed about the axis ofrotation of said engaging device, and said spring member is of thetorsion type having a portion thereof embracing said cylindricalsurface.

4. The device according to claim 1 wherein one of said races includes apair of cam surfaces, and wherein said gripper means includes a rollerselectively engageable with respective said cam surface responsive tothe direction of rotation of said driving member.

5. The device Iaccording to claim 1 wherein one of said races isdisposed eccentrically with respect to the other, and wherein saidgripper means includes a single roller wedging element disposed betweensaid races.

6. The device Iaccording to claim 1 wherein said races areconcentrically disposed with respect to each other, one of said racesincluding a plurality of pairs of cam surfaces, and wherein said grippermeans includes a plurality of roller elements, each of said rollerelements associated with a respective pair of said cam surfaces; saiddevice further including an annular cage member for receiving andpositioning said roller elements, :said cage member being operativelyassociated with said holding means for shifting the position of saidroller elements with respect to said cam surfaces responsive to thedirection of rotation of said driving member.

7. The device according to claim 3 wherein the opposite end portions ofsaid torsion spring are provided with prongs operatively engaged withsaid gripper means, said gripper means impelling said prongs to unwrapsaid embracing portion of said spring for said cylindrical surfaceresponsive to rotation of said driving member in either clockwise orcounter-clockwise direction.

References Cited UNITED STATES PATENTS 2,865,228 12/1958 Weismann 192-442,884,101 4/1959 Warn 192-44 3,055,471 9//1962 Warn 192-45 3,123,1693/1964 Young 192-36 FOREIGN PATENTS 843,046 7/1952 Germany.

CARLTON R. CROYLE, Primary Examiner. MARK NEWMAN, Examiner. C. M.LEEDOM, Assistant Examiner.

